Internal combustion engines having a plurality of valves for each cylinder typically use rocker arms mounted on a common pivot or axle. The rocker arms may include a hydraulic lash adjustment (HLA) assembly mounted near a valve tip of the rocker arm, to take up slack in the valvetrain. The HLA assembly typically includes an oil-containing chamber defined between an outer body and a plunger assembly slidably mounted within the outer body. A spring is arranged to enlarge the chamber by pushing the plunger assembly outwardly from the outer body to extend the HLA. Oil flows into the chamber via a one way valve, but can escape the chamber slowly, for example, via closely spaced leak down surfaces. The HLA can extend to accommodate any slack in the valve train assembly, for example, between a cam and a roller of the rocker arm.
The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.